The present invention relates to a process for preparing glyoxylic acid, and more particularly to an improved process for preparing glyoxylic acid by oxidizing glyoxal with nitric acid under particular conditions.
Glyoxylic acid has been commercially produced by oxidizing glyoxal with nitric acid in the presence or absence of sodium nitrite. According to this method, the yield of the glyoxylic acid to the consumed glyoxal is at most 60 to 75% by mole and carbon dioxide and organic acids such as oxalic acid are by-produced in large quantities. Further, a large quantity of nitric acid is consumed in the reaction, for instance, about 0.6 to 0.8 mole of nitric acid per mole of consumed glyoxal, and as a result, a large quantity of nitrogen oxides NOx generates.